Railway-traffic-controlling apparatus



H: A. THOMPSON RAILWAY TRAFFIC CONTROLLING APPARATUS July 3, 1928. 1,675,583

Filed Aug. 26, 1926 INVENTOR'Z H a WW- I a; 51- mm Patented July 3, 1928.

UNITED STATES PATENT OFFICE. i

HOWARD A. THOMPSON, 0F EDGEWOOD BOROUGH, PENNSYLVANIA, assmnon TO THE UNION SWITCH & SIGNAL COMPANY, OF SWISSVALE, PENNSYLVANIA, A com'om- TION OF PENNSYLVANIA.

" BAILWAY-TBAFFIC-CONTBOLLING APPARATUS.

Application filed August 26, 1926. serial No. 131,627.

My invention relates to railwa "traffic controlling apparatus, and particu arly to apparatus of the type comprising a plurality of sections of railway track separated by insulated joints and each provided with governing means controlled by current supplied to the rails of the section. One object of the invention is to prevent improper operation of the governing means for a section by stray current from an adjacent section.

I will describe several forms of railway traffic controlling apparatus embodying my invention, and will then point out the novel features thereof in claims.

In the accompanying drawing, Fig. 1 is a diagrammatic view illustrating one form of appparatusembodying my invention. Figs. 2 and 3 are views showing modified forms of the apparatus illustrated in Fig. .1 and also embodying my invention.

Similar reference characters refer to similar parts in each of the several views.

Referring first to Fig. 1, the reference characters 1 and 1 designate the track rails of a stretch of railway track over which traflic normally moves in the direction indicated by the arrow. These rails are divided into a plurality of successive track sections AB, B-C, etc. by short intermediate portions of track each designated by the reference character I) with an exponentcorrespending to the location and separated from the adjoining track sections by nsulated joints in the track rails. For example, the

short intermediate portion D dividing j I energ1zed,current is supplied to the operating mechanism of signal S from a seesection A-B from section B-C, is isolated from the rest of the track by means of two insulated joints 12 and 1 in rail landby two similar insulated joints 13 and 15 in rail 1. The two rails of each intermediate portion D are connected together bya jumper 19.

Each track section is provided with a suitable source of alternating track circuit current here shown as a track transformer designated by the referencecharacter T with a distinguishing exponent and having a secondary 6 connected across the rails adjacent theexit end of the section. The primary 7 of each track transformer is constantly supplied with alternating current froma secondary 9 of an associated line transformer designated by the reference character J with an exponent corresponding to the. location. impedance 8 is inter- ,posed between secondary 9 of each transformer J and primary 7 of the adjacent track transformer T. The primary 10 of each line transformer J is at all times supzplled with alternating current from a suit able source such. as an alternator M over line wires and 3*.

track relay R is constantly supplied with alternating current from secondary 9 of the adjacent line transformer J.

ach track section is therefore provided with a track circuit including the secondary 6 of a track transformer T, winding 5 of a track relay R, and the rails of the section in series, so that when the section is unoccupied the track relayis energized but that when the section is occupied the track relay "becomes tie-energized.

The track relays R maybe used tocontrol 'traflic governing means in any suitable manner. As here shown, each track sec 'tion is provided with a trackway si nal designated by the reference-character with an appropriate exponent and each capable of indicating proceed or stop. Each nal S is controlled by theiassociated track relay R. For example, when relay R is ondar 9 of transformer J over front contact '11 of relay R and the signal indicates proceed. When relay R is .de-energized,

however, the circuit is interrupted and the Under some conditions it may happen that one for more of the insulated joints 12, 13,14 or 15 breaks down. In this event, the track relay for one section may become improperly energized by stray current by an adjacent track section even though the former section is occupied by a train. For example, I will assume that insulated joints 12 and 14 adjacent point B both break down. Current may then flow from the lefthand terminal of secondary 6 of transformer T through rail 1 of section A-B, insulated joint 12, rail 1 of intermediate portion 1), insulated joint 14, rail 1 of section BC to the winding 5 of relay R rail 1 of section B-C, and thence through the ground to rail 1 of section A-B and back to the right-hand terminal of secondary 6 of transformer T The stray current thus supplied to winding 5 of relay R might be of suflicient magnitude to energize the relay. If this should occur signal S might indicate proceed, even though section BC were occupied by a train.

In order to prevent this undesirable occurrence, I connect the mid-point of the secondary 6 of each transformer T with one rail of the adjacent intermediate portion D.

Referring particularly to transformer T the mid-point of secondary 6 of this transformer is connected with rail 1 of the intermediate portion D Due to the jumper 19, the mid-point of secondary 6 is of course electrically connected also with rail 1 of the intermediate portion D lVith this arrangement, should either of the insulated joints 12 or 13 break down, a portion of the secondary of transformer T would be shortcircuited and track relay R would become deenergizcd, thereby causing signal S to indicate stop. Similarly, should insulated joints 12 and 13 both break down, the entire secondary 6 of transformer T would be short circuited and relay R would become tie-energized as explained above. Furthermore, should insulated joints 14 and 15 adjacent point B both break down, a direct shunt would be placed upon winding 5 of relay R thereby making it impossible for this relay to become energized by stray current from section A-B. \Vith the apparatus embodying my invention, therefore, it is impossible for a track relay for one section to become energized by stray current from an adjacent section due to a broke down insulated joint.

In the apparatus shown in Fig. 2, a fuse 17 is interposed between rail 1 of each. in

, termedi'ate portion and the midpoint of secondary 6 of the adjacent track transformer T. Each section is also provided with a detector relay designated by the reference character K with an appropriate exponent. Referring particularly to relay K this relay has one terminal connected directly with the right-hand terminal of track transform er T and the remaining terminal of the detector relay is connected with rail 1 of the intermediate portion I). The parts are so proportioned that under normal conditions the current supplied to the detector relay through the fuse 17 is not suflicient to blow out the fuse. Referring particularly to the apparatus located at point B, should either or both of insulated joints 12 or 13 break down, the increased current through fuse -17 due to the short circuit then placed upon the secondary of transformer T would blow out the fuse 17, thereby interrupting the circuit for relay K and allowing this relay to open. The front contact 16 of relay K controls the supply of current to winding 4 of track relay R so that relay R can not become energized unless relay K is also energized, even though current is supplied to winding 5 of the relay. It follows that if stray current is being supplied to winding 5 of relay R from section AB due to a broken down insulated joint, relay R cannot operate improperly, because the broken down insulated joint causes fuse 17 to blow out and open relay K thereby interrupting the circuit for winding 4 of relay R. It is therefore impossible to cause sig nal S to give a false proceed indication as the result of a broken down insulated joint between section B'G and section AB.

Under some conditions means are also provided for supplying each track section with train controlling loop current which flows through the rails of the section in parallel. As shown in Fig. 3 the immediate source of this train controlling current for each section is a transformer designated by the reference character L with an appropriate distinguishing exponent corresponding to the location, and having its primary 22 constantly supplied with alternating current from line wires 3 and 3*. section is also provided with an impedance 20 connected across the rails adjacent the entrance end of the section and a second impedance 18 connected across the rails adjacent the exit end of the section. Referring particularly to section A-B, the lefthand terminal of secondary 21'of transformer L is connected with the midpoint of impedance 20 and the right-hand terminal of this secondary is connected through an impedance 23 with rail 1 of 'the intermediate portion D Rail 1 of intermediate portion D is connected with the mid-point of impedance 18. Loop current fromtransformer L therefore flows through impedance 23, rail 1 of intermediate portion D jpmper 19. rail 1 of intermediate portion through the two halves of they impedance 18 in parallel, and the rails of section A-B in parallel, back through the two halves of the impedance 20 to secondary 21 of transformer L. The train controlling current supplied to the rails by the transformers L may be used to control train carried govern- Each track I rent to the rails of the section.

ing means in any suitable manner. In at least one form of apparatus suitable for co-operation with the trackway apparatus illustrated in Fig. 3 the simultaneous supply of track circuit current and train controlling loop current is necessary to give a proceed indication on board the train. $hould the supply of either of these currents be interrupted, a stop indication is received I on board the train. 7

In a railway tiafiic controlling system of the type described should either joint 12 or 13 adjacent point B break down, one half or the other of impedance 18 would be shortcircuited. The fluxes in the two halves of the impedance would then be unbalanced and the impedance would constitute a short circuit across the 'rails of section A-B, thereby shunting the transformer T and interrupting the supply of track circuit cur- Should a train enter the section A -B under these conditions it would receive a stop indication due to the absence of track circuit current. If either of insulated joints 14 or 15 breaks down, stray current from section A B could not be supplied to relay B, because, under this condition the potential applied from section A-B to section B-C would be the same as the ground potential of section AB and there would therefore be no potential available to supply current to winding 5 of relay R Furthermore, should the jumper 19 become broken, or should the connection between rail 1 of intermediate portion D and the mid-point of impedance 18 becomebroken, or should any other fault occur in the circuit for transformer L, the train controlling loop current would be interrupted and a stop indication would be received on board the train.

It follows from the foregoing that in each of the several views the short intermediate portion of track having its rails connected with the mid-point of an impedance (impedance 18 or secondary 6) connected across the rails of the section next in rear checks the condition of the adjacent insulated joints and makes it impossible for stray current flowing from one track section to an adjacent track section due to a broken down insulated joint to create a dangerous condition.

Although I have herein shown and described only three forms of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In combination, a stretch of railway track divided into two track sections by a short intermediate portion of track separated from both such sections by insulated joints in the track rails, a jumper for connecting the rails of such intermediate portion together,an impedance connected across the rails of one section, means for connecting an intermediate point of the impedance with a rail of the intermediate portion, means for creating an alternating electromotive force across the rails of such one section, and a relay connected across the rails of the other section.

2. In combination, astretch of railway track divided into two track sections by a short intermediate portion of track separated from both said sections by insulated joints, a transformer having its secondary connected across the rails of one said section, means for connecting the mid-point of said secondary with both rails of the intermediate portion, means for supplying alternating current to the primary of such transformer, and a track relay having a winding connected across the rails of the other sec tion.

3. In combination, a stretch of railway track divided into two track sections by a short intermediate portion of track separated from both said sections by insulated joints, a transformer having its secondary connected across the rails of one said section, means for connecting the mid-point of said secondary with both rails of the intermediate portion, means for supplying alternating current to the primary of such transformer, a detector relay connected across a portion of said secondary, a track relay having one winding connected across the rails of the other section, and means controlled by said detector relay for slmplying alternating current to the remaining winding of the track relay.

4. In combination, a stretch of railway track divided into two track sections by a short intermediate portion of track sepa rated from both said sections by insulated joints, a transformer having its terminals connected with the rails respectively of one said section, means including a fuse for connecting the midpoint of said secondary with both rails of said intermediate portion, means for supplying alternating current to the primary of said transformer, a detector relay having one terminal connected with a rail of the intermediate portion and the other terminal connected with a terminal of the secondary, a track relay having a winding connected across the rails of the other section, and a second winding on the track relay provided with a circuit including a front contact of the detector relay.

In testimony whereof I affix my signature.

HOWARD THOMPSON. 

